1. Field of Invention
This invention relates to compositions and methods for degrading, removing, and preventing bacterial cellulose and glyceride deposits. More particularly, this invention relates to enzymatic detergent compositions and methods of using them to degrade, remove, and prevent polymeric bacterial cellulose deposits in aqueous systems such as drain pipes. Additionally, this invention relates to enzymatic detergent compositions and methods of using them to degrade, remove, and prevent fatty and oily glyceride deposits in aqueous systems such as drain pipes.
2. Description of the Related Art
Traditional approaches to controlling or eliminating the problem of bacterial cellulose build-up in sugar or alcohol enriched drain systems typically have included contacting the cellulose with highly corrosive chemicals, such as concentrated hydrochloric acid, concentrated sulfuric acid, sodium hypochlorite, sodium silicate, chlorine bleach, phenylmercuric acetate, pentachlorophenol, tributyltin oxide, isocyanurates, or sodium hydroxide. However, these treatments have proven ineffective or incapable of removing deposited cellulosic slime, and they have several drawbacks associated with their use. Most of these chemicals are toxic to many organisms, including humans. Their toxicity makes them very dangerous during handling, and they contaminate and pollute if they are discharged into the enviroment. In addition to the problems engendered by toxicity, many of these toxic and hazardous chemicals can damage the drain systems where bacterial cellulose deposits are found.
Mechanical water jetting and rotor rooting are nontoxic alternatives to the chemical treatments described above. Of these, water jetting is preferred because it is less likely to cause damage to the drain systems. Yet neither method is an effective, acceptable treatment to prevent or remove bacterial cellulose deposits in drain systems. Bacterial cellulose accumulates rapidly in susceptible drain systems, and to keep such drains completely clear by these mechanical means requires frequent treatments. The frequent interruption in drain service occasioned by jetting or rooting makes them impractical. In addition, both methods involve significant manual labor, adding considerably to the cost of removing the deposits. Their cost and inefficiency make jetting or rooting uneconomical as prophylactic treatments. The result is that many drains having a bacterial cellulose problem are ineffectively and infrequently treated and therefore function at a severely reduced capacity or not at all.
Drain systems also have the problem of glyceride deposits resulting from grease effluents passing through the system. This problem is especially prevalent in the food service industry. Traditional treatments for controlling or eliminating the problem of glyceride deposits include the chemical treatment with highly corrosive chemicals and the mechanical water jetting and rotor rooting methods described above. However, the use of these traditional treatments for controlling or eliminating the glyceride deposits suffer the same disadvantages found in the traditional treatment of bacterial cellulose build-up.
U.S. Pat. No. 5,443,656 to Burrows et al. proposes a process for degrading fibrous cellulose materials, more particularly toilet tissue in aqueous waste holding tanks, by contacting the material with a composition comprising a cellulase enzyme, sodium bicarbonate, and citric acid. However, this method does not use an enzyme having activity specific to polymeric cellulose typically produced by microorganisms such as Acetobacter bacteria, and the enzyme concentrations disclosed are too low for effectively treating cellulose deposited by such microorganisms. Further, the method according to the Burrows patent does not disclose the use of any lipase enzyme. Moreover, compositions disclosed in this reference contain large quantities of sodium chloride, which drastically reduces cellulase enzyme activity under the conditions wherein the present invention is applied.
U.S. Pat. No. 3,506,582 to Gertzman discloses enzymatic drain cleaner compositions composed of a metal salt of carbonic acid, glucono-delta-lactone, and a mixture of enzymes, including amylase, protease, lipase, pectinase, and cellulase. These compositions suffer the same drawbacks found in the Burrows patent, i.e., they do not address the polymeric bacterial cellulose substrate produced by microorganisms such as Acetobacter bacteria, and they contain significant amounts of sodium chloride, which inhibits enzyme activity under the conditions where such bacterial cellulose deposits are found. Moreover, the disclosed compositions do not require an acid lipase enzymes specific to degrade oily and fatty materials, i.e., lipase enzymes having hydrolytic activity to ester bonds, specific to glyceride linkages.
U.S. Pat. No. 5,264,146 to Tobiason discloses a method and composition for carrying sewer or drain cleaning agents, including lipase and lipase excreting bacteria, to clean drains and sewer lines. This reference neither discloses nor suggests using an enzyme having activity specific to the troublesome cellulose deposited in sugar and alcohol enriched environments by microorganisms such as Acetobacter bacteria. Further, this reference suffers the same drawbacks found in the Gertzman patent; Tobiason fails to require that the lipase enzymes possess hydrolytic activity to ester bonds, specific to glyceride linkages. Moreover, the disclosed compositions can contain other cleaning agents, including corrosive chemicals such as caustic soda and harmful solvents such as dichlorobenzene.
U.S. Pat. Nos. 5,407,595 and 5,520,746 to Kamiya discloses a detergent drain pipe cleaning composition comprising a lipocatabolic lipase, an imbibing agent such as sodium bicarbonate, and an N-acyclic amino acid, but no cellulase enzyme. Thus, this composition also is not specific to cellulose produced by microorganisms such as Acetobacter bacteria, and therefore is not effective to address the problem solved by the present invention.
The drain systems in commercial service establishments, such as restaurants and bars, present a unique problem. In these establishments, particularly quick service restaurants, high quantities of fats, oils and grease produced by spillage, frying vats and washing sinks are found in the waste water. As the waste water passes through the drain system, glycerides from the fats, oils and grease deposit in the aqueous system. Additionally, bacterial cellulose deposits are also produced because of the presence of sugars and alcohols in the drain system. It is therefore common for these drain systems to have both bacterial cellulose deposits and glyceride deposits, with the glyceride deposits frequently absorbed onto the bacterial cellulose surface because of the bacterial cellulose's spongy nature and absorbtive capacity.
While concentrated sodium hydroxide or H.sub.2 SO.sub.4 will typically hydrolyze to the soluble fractions glyceride deposits from the fats, oils and grease, these corrosive chemicals are undesirable for use because of their toxicity and ineffectiveness in removing deposited cellulosic slime. Further, when the glyceride deposits are absorbed on the bacterial cellulose surface, it is very difficult for an acid cellulose enzyme to break down the deposits. In fact, the hydrolytic activity of the acid cellulose enzyme is reduced. Thus, an effective drain cleaner for the aqueous drain systems containing both bacterial cellulose deposits and glyceride deposits typically found in commercial service establishments is necessary. Prior to the present invention, there were no such commercial products available to address the drain system problems associated with both bacterial cellulose and glyceride deposits.